Autonomous self-assembling of large space telescopes for JWST follow-on, the effects of uncorrected polarization aberrations on exoplanet coronagraphy and precision polarimetry of exoplanet atmospheres, surfaces and dust rings are Dr. Breckinridge’s current research interests. Dr Breckinridge earned his BSc degree in Physics from Case Institute of Technology, Cleveland, OH in 1961 and his MSc and PhD in Optics at the University of Arizona, Tucson AZ. His dissertation was the development of the rotational shear spatial interferometer with applications to problems in the astronomical sciences. At JPL he was the instrument scientist for the ATMOS and the founding manager of the JPL Optics Section, which is responsible for the design, construction, and testing of most of the space-flight optical systems built by JPL. In 1994 Dr. Breckinridge became the JPL program manager for Innovative Optical Systems. In 1999 he accepted an assignment to the National Science Foundation (NSF) in Washington DC to manage the Advanced Technologies and Instruments program for the Astronomical Sciences Division. He returned to JPL in 2003 to become the chief technologist for the NASA exo-planet program. In Jan 2010 he retired from JPL after 33 years of service. Dr. Breckinridge taught the Optical Engineering class in the CALTECH Applied Physics and Aeronautics departments from 1983 to current. In 2003 he was the recipient of the George W. Goddard award of the SPIE. Dr. Breckinridge has over 95 publications in astronomy, physical optics, spectroscopy, and image science. Dr. Breckinridge currently holds an academic appointment at CALTECH as a visiting associate in Aeronautics and is an Adjunct Professor of Optics at the College of Optical Sciences at the University of Arizona, Tucson. He is a consultant in space optics systems and technology.

Publications (49)

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Previous papers have described our concept for a large telescope that would be assembled in space in several stages (in different configurations) over a period of fifteen to 20 years. Spreading the telescope development, launch and operations cost over 20 years would minimize the impact on NASA’s annual budget and drastically shorten the time between program start and “first light” for this space observatory. The first Stage of this Evolvable Space Telescope (EST) would consist of an instrument module located at the prime focus of three 4-meter hexagonal mirrors arranged in a semi-circle to form one-half of a 12-m segmented mirror. After several years three additional 4-m mirrors would be added to create a 12-m filled aperture. Later, twelve more 4-m mirrors will be added to this Stage 2 telescope to create a 20-m filled aperture space telescope. At each stage the telescope would have an unparalleled capability for UVOIR observations, and the results of these observations will guide the evolution of the telescope and its instruments. In this paper we describe our design concept for an initial configuration of our Evolvable Space Telescope that can meet the requirements of the 4-m version of the HabEx spacecraft currently under consideration by NASA’s Habitable Exoplanet Science and Technology Definition Team. This “Stage Zero” configuration will have only one 4-m mirror segment with the same 30-m focal length and a prime focus coronagraph with normal incidence optics to minimize polarization effects. After assembly and checkout in cis-lunar space, the telescope would transfer to a Sun-Earth L2 halo orbit and obtain high sensitivity, high resolution, high contrast UVOIR observations that address the scientific objectives of the Habitable-Exoplanet Imaging Missions.

Over the past few years, we have developed a concept for an evolvable space telescope (EST) that is assembled on orbit in three stages, growing from a 4×12-m telescope in Stage 1, to a 12-m filled aperture in Stage 2, and then to a 20-m filled aperture in Stage 3. Stage 1 is launched as a fully functional telescope and begins gathering science data immediately after checkout on orbit. This observatory is then periodically augmented in space with additional mirror segments, structures, and newer instruments to evolve the telescope over the years to a 20-m space telescope. We discuss the EST architecture, the motivation for this approach, and the benefits it provides over current approaches to building and maintaining large space observatories.

Conceptual architectures are now being developed to identify future directions for post JWST large space telescope systems to operate in the UV Optical and near IR regions of the spectrum. Here we show that the cost of optical surfaces within large aperture telescope/instrument systems can exceed $100M/reflection when expressed in terms of the aperture increase needed to over come internal absorption loss. We recommend a program in innovative optical design to minimize the number of surfaces by considering multiple functions for mirrors. An example is given using the Rowland circle imaging spectrometer systems for UV space science. With few exceptions, current space telescope architectures are based on systems optimized for ground-based astronomy. Both HST and JWST are classical “Cassegrain” telescopes derived from the ground-based tradition to co-locate the massive primary mirror and the instruments at the same end of the metrology structure. This requirement derives from the dual need to minimize observatory dome size and cost in the presence of the Earth’s 1-g gravitational field. Space telescopes, however function in the zero gravity of space and the 1- g constraint is relieved to the advantage of astronomers. Here we suggest that a prime focus large aperture telescope system in space may have potentially have higher transmittance, better pointing, improved thermal and structural control, less internal polarization and broader wavelength coverage than Cassegrain telescopes. An example is given showing how UV astronomy telescopes use single optical elements for multiple functions and therefore have a minimum number of reflections.

In this paper we apply a vector representation of physical optics, sometimes called polarization aberration theory to study image formation in astronomical telescopes and instruments. We describe image formation in-terms of interferometry and use the Fresnel polarization equations to show how light, upon propagation through an optical system become partially polarized. We make the observation that orthogonally polarized light does not interfere to form an intensity image. We show how the two polarization aberrations (diattenuation and and retardance) distort the system PSF, decrease transmittance, and increase unwanted background above that predicted using the nonphysical scalar models. We apply the polarization aberration theory (PolAbT) described earlier (Breckinridge, Lam and Chipman, 2015, PASP 127, 445-468) to the fore-optics of the system designed for AFTA-WFIRST– CGI to obtain a performance estimate. Analysis of the open-literature design using PolAbT leads us to estimate that the WFIRST-CGI contrast will be in the 10-5 regime at the occulting mask. Much above the levels predicted by others (Krist, Nemati and Mennesson, 2016, JATIS 2, 011003). Remind the reader: 1. Polarizers are operators, not filters in the same sense as colored filters, 2. Adaptive optics does not correct polarization aberrations, 3. Calculations of both diattenuation and retardance are needed to model real-world telescope/coronagraph systems.

The coronagraph instrument (CGI) on the Wide-Field Infrared Survey Telescope will directly image and spectrally characterize planets and circumstellar disks around nearby stars. Here we estimate the expected science yield of the CGI for known radial-velocity (RV) planets and potential circumstellar disks. The science return is estimated for three types of coronagraphs: the hybrid Lyot and shaped pupil are the currently planned designs, and the phase-induced amplitude apodizing complex mask coronagraph is the backup design. We compare the potential performance of each type for imaging as well as spectroscopy. We find that the RV targets can be imaged in sufficient numbers to produce substantial advances in the science of nearby exoplanets. To illustrate the potential for circumstellar disk detections, we estimate the brightness of zodiacal-type disks, which could be detected simultaneously during RV planet observations.

In 2014 we presented a concept for an Evolvable Space Telescope (EST) that was assembled on orbit in 3 stages, growing from a 4x12 meter telescope in Stage 1, to a 12-meter filled aperture in Stage 2, and then to a 20-meter filled aperture in Stage 3. Stage 1 is launched as a fully functional telescope and begins gathering science data immediately after checkout on orbit. This observatory is then periodically augmented in space with additional mirror segments, structures, and newer instruments to evolve the telescope over the years to a 20-meter space telescope. In this 2015 update of EST we focus upon three items: 1) a restructured Stage 1 EST with three mirror segments forming an off-axis telescope (half a 12-meter filled aperture); 2) more details on the value and architecture of the prime focus instrument accommodation; and 3) a more in depth discussion of the essential in-space infrastructure, early ground testing and a concept for an International Space Station testbed called MoDEST. In addition to the EST discussions we introduce a different alternative telescope architecture: a Rotating Synthetic Aperture (RSA). This is a rectangular primary mirror that can be rotated to fill the UV-plane. The original concept was developed by Raytheon Space and Airborne Systems for non-astronomical applications. In collaboration with Raytheon we have begun to explore the RSA approach as an astronomical space telescope and have initiated studies of science and cost performance.

The point spread function (PSF) for astronomical telescopes and instruments depends not only on geometric aberrations and scalar wave diffraction, but also on the apodization and wavefront errors introduced by coatings on reflecting and transmitting surfaces within the optical system. The functional form of these aberrations, called polarization aberrations, result from the angles of incidence and the variations of the coatings as a function of angle. These coatings induce small modifications to the PSF, which consists of four separate components, two nearly Airy-disk PSF components, and two faint components, we call ghost PSF components, with a spatial extent about twice the size of the diffraction limited image. As the specifications of optical systems constantly improve, these small effects become increasingly important. It is shown how the magnitude of these ghost PSF components, at ~10-5 in the example telescope, can interfere with exoplanet detection with coronagraphs.

I have two subjects I want to talk about today – one is on some historical experiences, and the other is about mistakes made in the development of high-performance optical systems, develop of functional requirements and flow-downs, identification of design approaches for an instrument, etc. One thing I'm working on relates to polarization and how it affects radiometry and the image quality of an optical system and so we’ll spend a little bit of time talking about that. Finally, though the HST failure has been widely covered, a few additional comments are probably also worthy of mention.

We present a review of the contributions by students, staff, faculty and alumni to the Nation’s space program over the past 50 years. The balloon polariscope led the way to future space optics missions. The missions Pioneer Venus (large probe solar flux radiometer), Pioneer 10/11 (imaging photopolarimeter) to Jupiter and Saturn, Hubble Space Telescope (HST), and next generation large aperture space telescopes are discussed.

Pursuing ground breaking science in a highly cost-constrained environment presents new challenges to the development of future space astrophysics missions. Within the conventional cost models for large observatories, executing a flagship “mission after next” appears to be unstainable. To achieve our nation’s science ambitions requires a new paradigm of system design, development and manufacture. This paper explores the nature of the current paradigm and proposes a series of steps to guide the entire community to a sustainable future.

Astronomical flagship missions after JWST will require affordable space telescopes and science instruments. Innovative spacecraft-electro-opto-mechanical system architectures matched to the science requirements are needed for observations for exoplanet characterization, cosmology, dark energy, galactic evolution formation of stars and planets, and many other research areas. The needs and requirements to perform this science will continue to drive us toward larger and larger apertures. Recent technology developments in precision station keeping of spacecraft, interplanetary transfer orbits, wavefront/sensing and control, laser engineering, macroscopic application of nano-technology, lossless optical designs, deployed structures, thermal management, interferometry, detectors and signal processing enable innovative telescope/system architectures with break-through performance. Unfortunately, NASA’s budget for Astrophysics is unlikely to be able to support the funding required for the 8 m to 16 m telescopes that have been studied as a follow-on to JWST using similar development/assembly approaches without decimating the rest of the Astrophysics Division’s budget. Consequently, we have been examining the feasibility of developing an “Evolvable Space Telescope” that would begin as a 3 to 4 m telescope when placed on orbit and then periodically be augmented with additional mirror segments, structures, and newer instruments to evolve the telescope and achieve the performance of a 16 m or larger space telescope. This paper reviews the approach for such a mission and identifies and discusses candidate architectures.

This paper suggests that the astronomical science data recorded with low F# telescopes for
applications requiring a known point spread function shape and those applications requiring instrument
polarization calibration may be compromised unless the effects of vector wave propagation are properly
modeled and compensated. Exoplanet coronagraphy requires “matched filter” masks and explicit designs
for the real and imaginary parts for the mask transmittance. Three aberration sources dominate image
quality in astronomical optical systems: amplitude, phase and polarization. Classical ray-trace aberration
analysis used today by optical engineers is inadequate to model image formation in modern low F# highperformance
astronomical telescopes. We show here that a complex (real and imaginary) vector wave
model is required for high performance, large aperture, very wide-field, low F# systems.
Self-induced polarization anisoplanatism (SIPA) reduces system image quality, decreases contrast
and limits the ability of image processing techniques to restore images. This paper provides a unique
analysis of the image formation process to identify measurements sensitive to SIPA. Both the real part and
the imaginary part of the vector complex wave needs to be traced through the entire optical system,
including each mirror surface, optical filter, and all masks. Only at the focal plane is the modulus squared
taken to obtain an estimate of the measured intensity.
This paper also discusses the concept of the polarization conjugate filter, suggested by the author
to correct telescope/instrument corrupted phase and amplitude and thus mitigate6, in part the effects of
phase and amplitude errors introduced by reflections of incoherent white-light from metal coatings.

Recent work, specifically the Lawrence Livermore National Laboratory (LLNL) Eyeglass and the DARPA MOIRE
programs, have evaluated lightweight, easily packaged and deployed, diffractive/refractive membrane transmissive
lenses as entrance apertures for large space and airborne telescopes. This presentation describes a new, innovative
approach to the theory of diffractive and refractive effects in lenses used as telescope entrance apertures and the
fabrication of the necessary large membrane optics. Analyses are presented to indicate how a broadband, highly
transmissive diffractive / refractive membrane lens can be developed and fabricated, and potential applications in defense
and astronomy are briefly discussed.

The white-light compensated rotational shear interferometer (coherence interferometer) was developed in an effort
to study the spatial frequency content of passively illuminated white-light scenes in real-time and to image sources
of astronomical interest at high spatial frequencies through atmospheric turbulence. This work was inspired by
Professor Goodman's studies of the image formation properties of coherent (laser) illuminated transparencies. We
discovered that real-time image processing is possible using white-light interferometry. The concept of a
quasimonoplanatic approximation is introduced as a parallel to the quasimonochromatic approximation needed to
describe the theory of Fourier transform spectrometers. This paper describes the coherence interferometer and
reviews its image formation properties under the conditions of quasimonoplanacity and describes its development
and its applications to physical optics, optical processing and astrophysics including the search for exoplanets.

Large aperture space telescopes are built with low F#'s to accommodate the mechanical constraints of launch vehicles
and to reduce resonance frequencies of the on-orbit system. Inherent with these low F# is Fresnel polarization which
effects image quality. We present the design and modeling of a nano-structure consisting of birefringent layers.
Analysis shows a device that functions across a 400nm bandwidth tunable from 300nm to 1200nm. This Fresnel
compensator device has a cross leakage of less than 0.001 retardance.

In order to facilitate the construction of future large space telescopes, the development of low cost, low mass
mirrors is necessary. However, such mirrors suffer from a lack of structural stability, stiffness, and shape accuracy.
Active materials and actuators can be used to alleviate this deficiency. For observations in the visible wavelengths,
the mirror surface must be controlled to an accuracy on the order of tens of nanometers. This paper presents
an exploration of several mirror design concepts and compares their effectiveness at providing accurate shape
control. The comparison test is the adjustment of a generic mirror from its manufactured spherical shape to the
shape required by various off-axis mirrors in a segmented primary mirror array. A study of thermal effects is
also presented and, from these results, a recommended design is chosen.

Since the first application of the telescope to astronomy in 1610, most new astronomical discoveries require larger and
larger radiation collecting areas. Today, the twin 10-meter Keck telescopes are operational and several 30-meter-aperture
class telescopes are being planned. Optical interferometers and sparse aperture ground telescopes for astronomy have
been proposed and built. Fienup showed the dependence between exposure time and the dilution factor of the aperture
needed to maintain image quality.1 Carpenter suggests a sparse aperture telescope system for the purpose of imaging
across the surfaces of stars.2 This paper demonstrates that the ability to reconstruct images from white-light extended
sources with different contrast levels also depends on the specific pupil topography that is applied to the telescope
system. Signal-to-noise ratios for recorded images are calculated for scene contrast, pupil shape, detector full-well,
detected photons, and exposure times.

We present a status report on a study on the effects of instrumental polarization on the fine structure of the stellar point spread function (PSF). These effects are important to understand because the the aberration caused by instrumental polarization on an otherwise diffraction-limited PSF will likely have have severe consequences for extreme high contrast imaging systems such as NASA's proposed Terrestrial Planet Finder (TPF) mission and the proposed NASA Eclipse mission. The report here, describing our efforts to examine these effects, includes two parts: 1) a numerical analysis of the effect of metallic reflection, with some polarization-specific retardation, on a spherical wavefront; 2) an experimental approach for observing this effect, along with a status report on preliminary laboratory results. The numerical analysis indicates that the inclusion of polarization-specific phase effects (retardation) results in a point spread function (PSF) aberration more severe than the amplitude (reflectivity) effects previously recorded in the literature. Preliminary in-lab results are consistent with our numerical predictions.

Novel optical design and engineering ideas are needed to build the large space telescopes for the direct detection and characterization of exo-solar system planets. For example, the Terrestrial Planet Finder Coronagraph requires a primary mirror 4 x 8 meters in size that is >10 x smoother than the 2.8 meter HST mirror and have a uniform reflectivity across the mirror to within 0.1%. The telescope system will need to control scattered light to within a part in 10 billion. The Terrestrial Planet Finder Interferometer will be a
white-light, broadband infrared interferometer with a baseline in excess of 50 meters. In addition to direct imaging, planets masses and orbits can be derived from very precise measurements of the position of a star as it moves across the background. Interferometers provide the highest accuracy measurements of relative positions
We will show that the optical design and the mechanical layout & configuration for these new telescopes need to be optimized for polarization as well as scattered light. Material science and coating
technology plays an important role in the optimization of these systems. Stress across the surface of a mirror and stress within the optical thin film introduces polarization dependent scattered light. A new method to measure the anisotropy of the polarization-reflectivity of thin metal films on large astronomical
mirrors is described.

Innovative optical designs are needed to create the space sensor systems of the future. The NASA mission development process has created several very challenging design and engineering problems. Three of these are discussed: The SAFIR is a 15 to 25 meter clear aperture telescope cooled to 4 degrees Kelvin, with spectrographs and imaging systems cooled to 1 degree Kelvin. The Terrestrial Planet Finder (TPF) will detect and characterize planets in orbit about other stars, The Stellar Interferometer (SI) will image across the surfaces of distant stars. Issues related to optical design & engineering and image quality will be discussed. This paper reviews the optical systems and engineering needs for next generation astrophysics missions.

To find evidence of life in the Universe outside our solar system is one of the most compelling and visionary adventures of the 21st century. The technologies to create the telescopes and instruments that will enable this discovery are now within the grasp of mankind. Direct imaging of a very faint planet around a neighboring bright star requires high contrast or a hypercontrast optical imaging system capable of controlling unwanted radiation within the system to one part in ten to the 11th. This paper identifies several physical phenomena that affect image quality in high contrast imaging systems. Polarization induced at curved metallic surfaces and by anisotropy in the deposition process (Smith-Purcell effect) along with beam shifts introduced by the Goos-Hachen effect are discussed. A typical configuration is analyzed, and technical risk mitigation concepts are discussed.

Recent advances in astronomical research have led to a much-improved understanding of the evolution of the physical Universe. Recent advances in biology and genetics have led to a much-improved understanding of our biological Universe. Scientists now believe that we have the research tools to begin to answer one of man’s two most compelling research questions: Are we alone? and How did we get here? This paper reviews the requirements and challenges we face to engineer and build the large space-based systems of interferometers and innovative single-aperture telescopes to detect and characterize in detail earth type planets around stars other than our sun.

The scientific and technical challenges facing the astronomical community during the next decade are discussed within the framework of new technology and technical management issues. The astronomical telescope and instrument communities of industry, academia and government need to be prepared to meet the challenges of 21st century Astronomy. Emphasis is given to ground-based optical and infrared astronomy.

Inflatable optics have the potential for large reduction in launch mass and volume, but they involve significant challenges to achieve the wavefront accuracy required for diffraction-limited operation in the visible and near IR. Current studies identify two major subsets of this topic: 1) inflation-deployed structures with a monolithic, but rolled, hyper-thin primary mirror and 2) an inflatable structure and inflatable membrane primary mirror. We address the current state of the art, the challenges involved, and a program development plan.

Applications of materials in white-light optical imaging, remote-sensing systems are discussed. Image formation in terms of wavefronts and the influence of materials on the quality of images is given. The rationale for why some space optics structures are large is presented. Other topics are applications of adaptive spectrometers, adaptive optics, and the control of unwanted radiation. Optical materials limit the next-generation high-performance optical systems.

An overview of the physical principals of imaging spectrometry for detailed characterization of remote objects and of gas vapors is given. The terms multi-spectral, hyperspectral, and ultra-spectral are defined within the framework of applications and instrument system design approaches. History of the development of imaging spectrometers is reviewed. We are at the threshold of major commercial efforts for these instrument systems.

A telescope folded into minimum volume for launching can be a powerful technique for maximizing the aperture size that can be accommodated in a given launch vehicle shroud. As an example we show our concept for a Folded Astronomical Space Telescope where a 2.4-m Hubble Space Telescope class of telescope can be packaged in a 1.5-m diameter cylinder. The enabling rationale, general configuration, and optical system technologies for such a telescope will be presented.

A Folded Astronomical Space Telescope is a 2.4-m Hubble Space Telescope class of telescope that can be packaged in a 1.5-m diameter cylinder through use of a single ring of eight deployable segments. Because it has less mass and uses a much smaller booster to inject it into orbit, the cost is greatly reduced. The enabling rationale, general configuration, and optical technologies for such a telescope are presented.

Several levels of wavefront control are necessary for the optimum performance of very large telescopes, especially segmented ones like the Large Deployable Reflector. In general, the major contributors to wavefront error are the segments of the large primary mirror. Wavefront control at the largest optical surface may not be the optimum choice because of the mass and inaccessibility of the elements of this surface that require upgrading. The concept of two-stage optics was developed to permit a poor wavefront from the large optics to be upgraded by means of a wavefront corrector at a small exit pupil of the system.

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SC726: Introduction to the Optical System Engineering of Remote Sensing Systems

Scientists and engineers use optical and infrared instruments to create images and make remote measurements. Quantitative measurements of the intensity, the wavelength content and the polarization content of white-light scenes, such as the Earth’s atmosphere and surface, astronomical objects, and laboratory sources are frequently needed. This short course is intended to provide the student with an understanding of the first order optical design principals behind several remote sensing optical systems. Examples are taken from recent optics challenges surrounding the design of imagers, astronomical coronagraphs, spectrometers and imaging spectrometers.

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Journal of Applied Remote SensingJournal of Astronomical Telescopes Instruments and SystemsJournal of Biomedical OpticsJournal of Electronic ImagingJournal of Medical ImagingJournal of Micro/Nanolithography, MEMS, and MOEMSJournal of NanophotonicsJournal of Photonics for EnergyNeurophotonicsOptical EngineeringSPIE Reviews